The Design Of Ground Penetrating Radar Of Ultra-wideband And High Power Signal Source

The transmitting signal source is a core component of the ground penetrating radar system,and its performance indicators have an important impact on the entire radar detection.At present,the mainstream ground penetrating radar system has a carrier impact pulse ground penetrating radar and a step frequency signal ground penetrating radar.The carrier-free shock pulse ground penetrating radar emits a nanosecond shock pulse.The echo signal is used to identify the target.How to develop a high-stability nanosecond pulse source is a key.This paper uses avalanche tube Marx cascade plus end.The reflection line method produces a high-power ultra-wideband nanosecond bipolar shock pulse source,and the power synthesis experiment is performed on the avalanche tube Marx pulse source by microwave power synthesis;the step frequency ground penetrating radar uses discrete steps.The frequency signal is synthesized into a one-dimensional range image.Due to the higher average power,the shock pulse radar system can not meet the requirements of high distribution rate and long-distance penetration detection performance.Research and design of broadband,high-power,and agile steps The frequency source is of great significance.This article is divided into six chapters.The first chapter introduces the research background,significance and research status of the thesis.The second chapter introduces some commonly used ultra-wideband ground penetrating radar signals and their generation techniques.The next two chapters detail the design process of the shock pulse signal source and the step frequency signal source.Finally,the signal source performance indicators were tested.For the design of the shock pulse signal source,the avalanche tube Marx circuit is selected.Firstly,the principle of avalanche tube pulse generation is introduced in detail,and the theoretical calculation of related parameters is carried out.Secondly,some simulations are performed using Orcad Pspice simulation software.Optimization,finally using Altium designer for PCB design,detailing the design process of bipolar Gaussian pulse generated by avalanche tube Marx circuit,designing a high stability bipolar shock pulse source with peak voltage greater than 1kV The tail is less than 10%of the peak-to-peak value,the time base jitter is less than 50 ps,and the peak amplitude jitter is less than 5% of the peak-to-peak amplitude.Next,considering the limitations ofthe avalanche tube Marx circuit in terms of pulse peak power boost,a multisection Wilkinson wideband power synthesizer was designed to improve the peak by power synthesis of the avalanche Marx circuit sub-module.The output power,the peak voltage superposition efficiency is 66%,and the peak power superposition efficiency is 80%.Then,for the design of the step frequency signal source,a direct digital frequency synthesis method with fast frequency modulation is adopted,and detailed scheme design is carried out,including DDS signal source circuit,PLL reference clock circuit,wideband power amplifier circuit and power supply circuit.Finally,the relevant performance indicators are tested.The specific indicators of the step frequency source are: output frequency 100M-1.4GHz;phase noise less than125dBc@50kHz;broadband spur suppression less than-50dBc;output average power 1W.